Electric push-button switch

ABSTRACT

A push button switch having a push button installed in a switch housing wherein the push button is joined to the housing by two levers which are pivotally mounted on the housing and pivotally mounted on the push button and a link pivotally connected to the levers.

SPECIFICATION

The invention relates to an electric push-button switch, notably forautomobiles, with a push button which, spring-loaded, is installed inthe switch housing and joined to it in articulate fashion, by means oftwo levers which are arranged, for one, on a bearing in the housing and,for another, on a bearing in the push button, which bearing pivots aboutthe aforementioned bearing, each lever featuring a projection with anentrainment bearing, and the two entrainment bearings being connected bya bar.

A push-button switch of this type is known from FR-A-2 175 105. Itfeatures a housing and a push button, where the push button is joined tothe housing in articulate fashion, by means of two levers which arearranged on the push button, for one, on a stationary bearing in thehousing and, for another, in a stationary bearing which pivots about thehousing-specific bearing. The levers are comprised of triangular partswhose one point is occupied by the stationary bearing in the housing,the second point by the stationary bearing on the push button, and thethird point by an entrainment bearing, with both entrainment bearingsconnected by a bar. The part of the triangle that connects thestationary bearing in the housing with the stationary bearing on thepush button can be considered as the lever proper, while the remainingpart may be considered as a projection that is integrally molded on.Following its actuation, the push button is restored to its startingposition by a spring contained in the switch.

The objective underlying the invention is to provide an electricpush-button switch of the initially mentioned type where the pushbutton, when actuated one-sidedly, can be moved evenly, without skewingand binding, with at the same time large play between push button andhousing as well as given tolerance compensation.

This objective is inventionally accomplished in that

the housing-specific bearing for the one lever is stationary while thehousing-specific bearing for the other lever is fashioned as a slot inthe housing, and

an elastic element acting against the push button engages the projectionof the lever retained in the slot.

Besides a reliable actuation of the push-button switch, this measureaccomplishes a tolerance compensation, since the force of the elasticelement which is introduced via the projection on one of the levers andvia the bar and against the working direction of the push button causesa fixing of the push button against the elastic element acting in thedirection of said push button.

The embodiment of the invention provides for four levers which connectthe housing in articulate fashion with the push button, where two leverseach are aligned coaxially and connected by a bar. Accomplished thereby,when arranging the levers beneath the corners of a larger-area pushbutton, is a frictionless depression of the push button, with thecoaxial connection of two levers each effecting a forced entrainment ofthe two coaxial levers. The four levers, between the housing and thepush button, are suitably connected by way of the bars mounted in theirentrainment bearings, with a rail between the two bars. Thus, thedisplacement path is being transmitted from bar to bar, directly via therail. Each lever is preferably connected to the pertaining bar by meansof a clip or integrally via a film hinge.

To restrict the maximum path of the push button out of the housing, afurther embodiment provides on the housing for a stop on which rests theprojection of one of the levers under the effect of the elastic elementacting on the push button. This establishment of the outer switchingposition of the push button produces an even bearing of the leverprojection on the stop, assuring an easy detachment of the projectionfrom the stop in actuating the push button.

Arranged in the housing is suitably a printed circuit board with aswitching element mounted on it, the spring-loaded button of whichelement causes the push button to restore automatically. Also installedon the printed circuit board is preferably an illuminating element whosebulb is received in the opening of a luminescent screen. Using a printedcircuit board with components arranged on it makes it possible to obtainin a simple fashion different wiring patterns and switching functions,without involving any change in the type of assembly.

To obtain a defined illumination of the push button, an advancement ofthe invention provides for fabricating the push button as a two-colorinjection-molded part whose outer shell is luminescent and its innershell opaque, with brackets molded to the inner shell for a clipconnection with the luminescent screen, and posts for receiving thepivot bearings. The material of the inner shell is thus able towithstand the high stresses of the clip connection, and the material ofthe outer shell is available evenly over the entire surface of the pushbutton. Hence, also a desired symbol can be molded in the push button.

An alternative way to accomplish the objective underlying the inventionis characterized in that in the housing there is arranged a guidesurface on which bears the bar under the effect of an elastic element,with the entrainment bearings in the bar fashioned as slot and matchingpins molded to the projection of the levers for engagement of the slots.The elastic element bears preferably with its one end on the bottom of ablind hole in the bar and with its other end on a contact bridge, withentrainment shoulders of the contact bridge fitted in openings in thebar and with the contact bridge interacting with electric contacts inthe bottom of the housing. Achieved thereby, besides a reliableactuation of the push-button switch as well as the tolerancecompensation, are high currents and switching capacities with thepush-button switch. Furthermore, the bar serves two functions, namelythe forced entrainment of the levers and, thus, the push button, andadditionally the function of a switching member, with the bar guidingthe contact bridge and a sufficient contact force being always availablethrough the compression spring underneath the contact bridge. The bottomof the housing may be designed differently, whereby also other switchingstates are achieved after exchange. Mounted at the bottom of the housingis suitably an illuminating element whose bulb is received in theopening of a luminescent screen.

The following description explains the invention in greater detail, withthe aid of the drawing. The push-button switch illustrated in FIG. 1through 6 is not an embodiment of the invention, but only an exampleserving to facilitate understanding the invention. The drawing shows in

FIG. 1, a view of the long side of an electric push-button switch;

FIG. 2, a side elevation of the electric push-button switch in thedirection of arrow II;

FIG. 3, a section through an electric push-button switch according toFIG. 2 along line III-III, in unactuated state;

FIG. 4, a section through the electric push-button switch according toFIG. 3 in actuated state;

FIG. 5, a half-section through the electric push-button switch accordingto FIG. 2 along line V-V;

FIG. 6, a section through the electric push-button switch according toFIG. 1, along line VI-VI;

FIG. 7, an embodiment of the electric push-button switch according tothe invention;

FIG. 8, an alternative embodiment of the electric push-button switchaccording to the invention.

The electric push-button switch has a cross-sectionally rectangularhousing 1, a flange 2 surrounding the housing 1 and on it a skirt 3. Thepush button 4 reaches with its edge 5 over the skirt 3 of the housing 1.On the narrow sides of the rectangular housing 1, elastic clips 6 aremounted in a groove 8 over a serration 7. Guide strips 9 are molded tothe long side of the housing 1 of the electric push-button switch. Theelectric pushbutton switch is mounted on a not illustrated panel withthe aid of the clips 6 and guide strips 9; the flange 2 rests then onthe top side of the panel. FIG. 1 and 2 show the electric push-buttonswitch in its unactuated state; the double-dot-dash line shows thepush-button switch 4 in its actuated state. Connector pins 11, forconnection by means of a plug, are arranged in a receptacle 10.

In FIG. 3, guide elements 12 are visible, which consist of a lever 13connecting the housing 1 and the push button 4 in jointed fashion. Thelever 13 is arranged, for one, around a stationary bearing 14 in thehousing 1 and, for another, on a stationary bearing 15, on the pushbutton, which pivots about the housing-fixed bearing 14.

In the exemplary embodiment, four levers 13 are fitted between thehousing 1 and the push-button 4, with two levers 13 each alignedcoaxially and available in one-piece fashion via beams 16. For reason ofmaterial s, the beams 16 are fashioned as flat disks. To achieve a moreconvenient assembly of the levers 13 with the interposing beams 16 inthe housing 1, this connection is designed as a clip 17: a clip 18allows easy assembly of the lever to the push-button 4.

Molded integrally to the lever 13 is a projection 19 on the end 20 ofwhich an entrainment bearing 21 is provided which pivots about thestationary bearing 14 in the housing 1. The entrainment bearing 21located on the projection 19 of lever 13 is arranged pezpendicularly tothe connecting line 27 between the stationary bearing 14 in the housing1 and the pivotable bearing 15 on the push-button 4, wherein it standsis vertically on the axis of the stationary bearing 14 in the housing 1.

A further forced entrainment occurs in that at least two levers 13 withsame pivoting direction of the projection 19 in the pivoting directionof entrainment bearing 21 are connected by a bar 22 by means of clips23. Molded integrally to the beam 16 is a projection 24 that assuresstability of the projections 19.

As the push-button 4 is actuated, the lever 13 pivots about thestationary bearing 14 in the housing 1, and the pivoting bearing 15 onthe push-button 4 as well as the entrainment bearing 21 on theprojection 19 clockwise and, as the push-button 4 is released, the lever4 pivots with its molded ba s 15 and 21 counterclockwise. The forcedentrainment is improved in that the four levers 13 between the housing 1and the push-button 4 are by way of the bars 22, which are mounted intheir entrainment bearings 21, connected to a rail 25 between the bars22. The entrainment is thus direct and is not influenced additionally bymanufacturing tolerances.

In the unactuated state of the push-button 4, which under the effect ofan elastic element 28 is forced outward, the projection 19 bears on astop 26 that limits the actuation stroke upwardly, AS the push-button 4is actuated, the projection 19 swings away from the stop 26. In doingso, the push-button 4 is against the effect of the elastic element 28which, for one, is contained in switching element 29, or alternativelyis mounted between he circuit board 30 and a receiving means 31 on thepush-button 4.

FIG. 7 shows an alternative embodiment. Here, with levers 13 connectedby bars 22, a lever 13 is fitted in a stationary bearing 14 in thehousing 1, and the bearings 32 for all further levers 33 are formed eachby a slot 34 in the housing 1. Attached to the projection 19 of the lev33 fitted in the slot 34 is a compression spring 35, its workingdirection being opposite to the push-button 4. For mounting thecompression spring 35 on the beam projection 24 of lever 33, a pin 36 ismolded to it and a depression 37 is molded in the housing 1, whose innerarea is fashioned as a bowl 38 in which the compression spring 35 islocated. Hence, the compression spring 35 bears with its one end on theinside wall of the housing 1 and with its other end on the beamprojection 24 of lever 33.

Mounted in the housing 1 is a printed circuit board 30 containing aswitching element 29. Provided in the switching element 29 is an elasticelement 28 which moves the switching button 39 of the switching element29 automatically to the outer switching position. A plunger 40 of thepush-button 4 bears on the top side of the switching button 39 of theswitching element 29, by way of which plunger the push-button 4 is movedto the outer switching position. The printed circuit board 30 containsthe not illustrated lines for realizing the current paths between theconnector pins 11, switching element 29 and illuminating element 41. Theconnector pins 11 and the switching element 29 are soldered in place,while the illuminating element 41 is mounted detachable. The top side ofthe printed circuit 30 contains a pilot pin 42 which fixes the elasticelement 28 in its position. The connector pins 11 are bent over at rightangles, and the housing 1 has in the area of the bend a void 43. Theilluminating element 41 contains a bulb 60 that enters the interior ofthe luminescent screen 44 through the opening 45.

Illustrated in FIG. 1 is an alternative embodiment of the bar 22. Inthis exemplary embodiment, the housing 1 features a guide surface 46 onwhich the bar 22 bears under the effect of a compression spring 47. Thebar 22 moves on this guide surface 46 always linearly. To enable such,the entrainment bearings 48 of the bar 22 are fashioned as slots 49, andappropriate pins 51 are molded to the projection 19 of the lever 13,which pins engage the slots 49 in the bar 22. The bar 22 iscross-sectionally appreciably wider and assumes the function of aswitching member, in that the compression spring 47 bears with one end50 on the bottom 52 of a blind hole 53 in the bar 22 and with its otherend 54 on a contact bridge 55, the entrainment shoulder 56 of thecontact bridge 55 being fitted in openings 57 of the bar 22 and thecontact bridge 55 interacting in the bottom 59 of housing 1 withcontacts 58 that lead to the connector pins 11. The bottom 59 isfastened to the housing 1 by a not illustrated clip. Fastened to thebottom 59 of the housing 51 is an illuminating element 41, the bulb 60of which is received in the opening 45 of a luminescent screen 44.

The push-button 4 is fabricated as a two-color injection molding whoseouter shell 61 consists of luminescent material, while its inner shell62 is opaque. The bracket 63 molded to the inner shell 62, for a clip 64of the luminescent screen 44, and the shanks 65 for receiving thepivoting bearings 15 of the push-button 4 are molded integrally.Besides, guide bracken 66 are molded to the inner shell, which arereceived in the housing 1 with much backlash.

We claim:
 1. A push-button switch assembly comprising:(a) a housinghaving a switching element therein with a moveable actuator; (b) a pairof levers each pivotally mounted in spaced relationship on said housingfor pivotal movement thereon about substantially parallel axes; (c) alink having an end portion thereof pivotally connected to each of saidlevers on a common side of said pivotal mounts; (d) an elongatedpush-button having an end portion pivotally connected to each of saidlevers on a common side of said pivotal mounts; and, (e) means biasingsaid push-button in a direction outwardly of said housing, wherein saidpivotal mount for one of said levers is disposed for sliding movement onsaid housing.
 2. The switch assembly defined in claim 1 wherein saidpush-button, said levers and said link are arranged as a four-barlinkage.
 3. The switch assembly defined in claim 1 wherein said linkcomprises a pair of bars disposed in spaced parallel arrangement witheach bar disposed on an opposite side of said levers.
 4. The switchassembly defined in claim 1 wherein each of said levers includesintegrally formed therewith a film hinge for retaining an end of saidlink pivotally connected thereto.
 5. The switch assembly defined inclaim 1 wherein said pivotal connection of said link to each of saidlevers comprises a pin molded as part of each lever, with each said pinengaging a slot in said link.
 6. The switch assembly defined in claim 1wherein said switch element includes a stationary contact associatedwith said housing and a moveable contact associated with said link. 7.The switch assembly defined in claim 1 wherein said switch elementincludes a moveable contact associated with said link and a stationarycontact associated with said housing, wherein said moveable contact isresiliently biased against said stationary contact.
 8. The switchassembly defined in claim 1 wherein said pivotal connection of saidlevers to said link includes a slotted connection.